There is concern about brain aluminum accumulation over the life span that might contribute to Alzheimer's disease and related neurodegenerative disorders. The overall objective of the proposed research is to test the null hypothesis that the bioavailability of Al is comparable from foods and from drinking water. If the null hypothesis is accepted the concern about Al intake for typical Americans should focus on food and not drinking water. The specific aims are to produce food products containing 26Al in the normal chemical species for these foods and determine Al oral bioavailability from these selected representative foods, compared to Al oral bioavailability from drinking water. Foods to be produced are a baked good and a processed cheese, in which 26Al will be incorporated during food production, and spinach and tea, in which 26Al will be incorporated during their hydroponic production. Al bioavailability will be determined from the area under the serum 26Al concentration x time curve after bolus administration of the 26Al-containing food compared to the equivalent term obtained from serum 27Al concentration produced by continuous intravenous 27Al infusion throughout the study. 26Al will be analyzed by accelerator mass spectroscopy; 27Al by atomic absorption spectroscopy. It is hypothesized that oral Al bioavailability from food will be less than from water, due to Al binding to food components that inhibit its absorption. The results will resolve the controversy whether drinking water contributes a significant amount of the Al that is absorbed by the human. The results will suggest whether health-based standards to regulate Al in drinking water should be considered by regulatory agencies or whether reduction of absorbed Al in the human can be more effectively achieved by reducing Al in foods.